Messages in this thread | | | Subject | Re: GPLv3 Position Statement | From | Krzysztof Halasa <> | Date | Wed, 27 Sep 2006 22:34:21 +0200 |
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I generally agree with you, but...
Linus Torvalds <torvalds@osdl.org> writes:
> And it not at all uncommon to have a flash that simply cannot be upgraded > without opening the box. Even a lot of PC's have that: a lot (most?) PC's > have a flash that has a separate _hardware_ pin that says that it is > (possibly just partially) read-only. So in order to upgrade it, you'd > literally need to open the case up, set a jumper, and _then_ run the > program to reflash it.
I think this is history. Yes, late 486s and Pentiums (60 and 66?) had a jumper protecting the flash. It's not true since ca. "Pentium 75+" days - while many boards use "bootblock" chips, it's (almost?) always unprotected (at most it just requires setting some GPIO pin(s)). The rest of flash obviously has to be R/W to support the ESCD etc.
I think there are systems with 2 copies of the whole BIOS, and the user selects the copy with a jumper (probably connected directly to the most significant address line of the flash IC) - the second copy might theoretically use a R/O bootblock but I've never checked it.
Most VGAs, disks, PCI cards etc. have flash chips with no protection either, and I have to say I felt much better when they used (EP)ROMs.
I think almost all hardware manufacturers use a blank flash chips, programming them "in system" with things like JTAG. -- Krzysztof Halasa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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